The Zilog Z80 microprocessor was released circa March 1976. The CPU replaces the earlier Intel 8008 processor, The Z80 was a renegade processor when some engineers left Intel to form their own company. The Z80 is a clone of the Intel C8080A with some extensions. Zilog added some more registers and they also made the CPU much …

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Floppy disks

The original DA400 provided only 80.6K when formatted with 128 byte sectors and 89.6K when formatted with 256 byte sectors. The Tandon floppy disk on the PC used 256 byte sectors and it held 160K on each side of the diskette. The PC diskette is termed double density as it is double the capacity of …

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tic tac toe board

Back in 1975 we developed a version of Tic Tac Toe that runs on the IBM System 360 or System 370 mainframe using a standard 3270 terminal. FORTRAN is standard for all mainframes from 1958 onwards. The code shown is standard FORTRAN IV which IBM developed and its largely compatible with more recent standards. FORTRAN …

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power mosfet

The power supply in the PC has evolved over time however the basic technology has remained the same. Most of the changes over the years were driven by many different forces. BRIDGE RECTIFIER It takes 4 power diodes to covert the 115V AC to about 150VDC.  The reason the voltage is higher is that DC …

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In 1974, Dr. Gary A. Kildall, while working for Intel, created CP/M as the first operating system for the new microprocessor. CP/M based machines helped propel personal computers in the 1970s. Machines were much less expensive than mainframe based solutions. Intel 8080 Intel 8085 Zilog Z80 The early 8-bit processors topped out at 64KB of memory. …

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The Intel C8080A microprocessor was released circa April 1974. The CPU replaces the earlier Intel 8008 processor, Once CP/M was ready, the 8080 became a successful platform for business machines. As the 1970s unfolded large numbers of machines were designed and built. The C8080A is largely 8-bit however it does add some 16-bit instructions not available …

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During the mid to late 1960s, many early video games were programmed on mainframe computers. Developed prior to the rise of the commercial video game industry in the early 1970s, these early mainframe games were generally written by students or employees at large corporations. Games were written in Assembler as the high level languages available …

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Networking got its start back in the 1950s with RADAR systems and mainframe systems. Ethernet came from Robert Metcalf’s PhD dissertation in 1973. Eventually this was standardized by the IEEE as 802.3 working group. In the early days DOS machines used coaxial cables to wire up a group of machines into a local area network, …

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Pong was released on November 29, 1972 by Atari who also developed the game. Pong is a coin-op cabinet simulation game. Pong is a game for 2 players. Each player operates a “paddle” via an analog knob. The object is to bounce the “ball” back and forth. The ball bounce had multiple angles to make the …

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Chess, checkers, Monopoly and so on are all very old. Board games have been discovered even in the ruins of old villages and towns. Early mainframe games were inspired by classic board games,  Some games are based on pure strategy, but many contain an element of chance; and some are purely chance, with no element of …

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Michigan Terminal Systems is an operating system for the IBM System 360 that supports IBM 3270 terminals. MTS grew out of the University’s IBM 3070 mainframe which was used a batch processing model. The university wanted to move to an interactive approach which would allow teams to work on the system. After a year of …

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In the early days the first printer we had used was the IBM 1403. In 1970,  the model 7 was in use with the IBM System 360 mainframes. The 1403 used a chain and a bank of solenoid hammers to print letters on a line. The ink ribbon was a long roll the width of …

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Back in the early 1980s the use of a 32-bit MBR index was believed to adequate. Hard disks from the 1956 to 1981 had not even made it much past 1GB with mainframes. The IBM 350 Disk Storage Unit (image), released in 1956, consisted of the magnetic disk memory unit with its access mechanism, the …

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Monopoly was released in 1903 by Elizabeth Magie and Charles Farrow who also developed the game. Monopoly is a board game. Today Hasbro owns the rights to the game. They have modified the game several times to perpetuate the copyright and trademark. Monopoly was designed as a way to demonstrate that an economy which rewards wealth creation …

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